Schotte Manufacturing Company uses two different independent variables (machine- hours and number of packages) in two different equations to evaluate costs of the packaging department. The most recent results of the two regressions are as follows: Machine-hours: Variable Constant Independent Variable r = 0.33 Number of packages: Variable Constant Independent Variable r = 0.73 Required: Coefficient 748.30 Standard Error t-Value 341.20 2.19 52.90 35.20 1.50 Coefficient 242.90 Standard Error 75.04 t-Value 3.24 5.60 2.00 2.80 a. What are the estimating equations for each cost driver? b. Which cost driver is best and why?